[Samba] io_uring cause data corruption

[Jeremy Allison]

On Mon, Apr 27, 2020 at 10:27:17AM +0200, A L via samba wrote:
> 
> On 2020-04-26 19:46, Jeremy Allison via samba wrote:
> > On Sun, Apr 26, 2020 at 11:51:42AM +0200, A L via samba wrote:
> > > * Connected from a Windows 10 computer over 1G ethernet. * Copy data
> > > using Windows Explorer and FastCopy(1) from the Samba share to a
> > > local disk. * Verify the sha-256 sum on the files. From what I can
> > > see there is data corruption on many of the files. Sha-256 does not
> > > match. I copied the same files many times and the data corruption
> > > occurs within minutes. The total data set is about 800GB.
> > Can you do checksums on file fragments so we can discover at what offset
> > (if non-zero) the corruption occurs.
> Yes, I will check this.
> 
> I saw a patch on the kernel mailing list about possible corruptions in
> during re-scheduling. I wonder if this is the problem I am hitting. I'll
> make some more tests with this patch.
> https://www.spinics.net/lists/io-uring/msg01706.html

Oh, that might explain it. I won't do further work
until you can confirm the Samba corruptions happen
with this kernel patch also.